Android手機的CPU的頻率資訊被儲存在 /sys/devices/system/cpu/cpu0/cpufreq 目錄下，通過shell命令檢視該目錄下的檔案，如下圖

其中cpuinfo_cur_freq檔案儲存CPU當前頻率，cpuinfo_max_freq儲存CPU可執行最大頻率，cpuinfo_min_freq儲存CPU可執行最小頻率。通過定時讀取這些檔案便可實時獲取CPU頻率。

1.建立getCPU類，獲取CPU頻率資訊。

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import
 
 java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class getCPU {

    private final static String CurPath = "/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq";//儲存當前CPU頻率
    //獲取當前CPU頻率
    public static int getCurCPU(){
        int result = 0;
        FileReader fr = null
 
;
        BufferedReader br = null;
        try{
            fr = new FileReader(CurPath);
            br = new BufferedReader(fr);
            String text = br.readLine();
            result = Integer.parseInt(text.trim());
        }catch (FileNotFoundException e){
            e.printStackTrace();
        }catch
 
 (IOException e){
            e.printStackTrace();
        }finally {
            if (fr != null)
                try{
                    fr.close();
                }catch (IOException e){
                    e.printStackTrace();
                }
            if (br != null)
                try{
                    br.close();
                }catch (IOException e){
                    e.printStackTrace();
                }
        }
        return result;
    }

private final static String MaxPath = "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq";//儲存CPU可執行最大頻率
    //獲取CPU可執行最大頻率
    public static int getMaxCPU(){
        int result = 0;
        FileReader fr = null;
        BufferedReader br = null;
        try{
            fr = new FileReader(MaxPath);
            br = new BufferedReader(fr);
            String text = br.readLine();
            result = Integer.parseInt(text.trim());
        }catch (FileNotFoundException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            if (fr != null)
                try{
                    fr.close();
                }catch (IOException e){
                    e.printStackTrace();
                }
            if (br != null)
                try{
                    br.close();
                }catch (IOException e){
                    e.printStackTrace();
                }
        }
        return result;
    }

   private final static String MinPath = "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq";//儲存CPU可執行最小頻率
    //獲取CPU可執行最小頻率
    public static int getMinCPU(){
        int result = 0;
        FileReader fr = null;
        BufferedReader br = null;
        try{
            fr = new FileReader(MinPath);
            br = new BufferedReader(fr);
            String text = br.readLine();
            result = Integer.parseInt(text.trim());
        }catch (FileNotFoundException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            if (fr != null)
                try{
                    fr.close();
                }catch (IOException e){
                    e.printStackTrace();
                }
            if (br != null)
                try{
                    br.close();
                }catch (IOException e){
                    e.printStackTrace();
                }
        }
        return result;
    }
}

2.MainActivity

public class MainActivity extends Activity {
    private TextView textView1;
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView1 = (TextView) findViewById(R.id.show_CPU);
        new Thread(){
            public void run(){
                try{
                    while (true){
                        Thread.sleep(30000);//設定時間間隔為30s
                        Message msg = new Message();
                        msg.what = UPDATE;
                        handler.sendMessage(msg);
                    }
                }catch (InterruptedException e){
                    e.printStackTrace();
                }
            }
        }.start();
    }

    getCPU getcpu = new getCPU();
    private static final int UPDATE = 0;
    private Handler handler = new Handler(){
        public void handleMessage(Message msg){
            switch (msg.what){
                case UPDATE:
                    textView1.setText("");
                    textView1.append("CPU最大頻率為："+ Integer.toString(getcpu.getMaxCPU()) + "\n");
                    textView1.append("CPU最小頻率為："+ Integer.toString(getcpu.getMinCPU()) + "\n");
                    textView1.append("CPU當前頻率為："+ Integer.toString(getcpu.getCurCPU()) + "\n");
                    break;
                default:
                    break;
            }
            super.handleMessage(msg);
        }
    };

}

3.activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:weightSum="1">    
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/show_CPU" />
</LinearLayout>

執行效果如圖，可以看出實現了實時獲取CPU的頻率。